Methacrylic resins have excellent transparency, appearance, weatherability, gloss and processability and, therefore, have been industrially used in large amounts in various fields. However, they have an essential drawback of being poor in impact resistance. In general, improvement of the impact resistance of methacrylic resins has been made by introducing a multilayer-structured material having a rubber phase to methacrylic resins to form a two phase structure to thereby impart a strength, and various proposals based thereon have been made.
For example, Japanese Patent Publication Kokoku No. 55-27576 discloses improving the impact resistance of methacrylic resins by incorporating methacrylic resins with a polymer having a three layer structure prepared by polymerizing a monomer component containing methyl methacrylate as a main component to form an innermost layer, then polymerizing a second monomer component containing butyl acrylate as a main component in the presence of the innermost layer to form a second layer on the innermost layer, and further polymerizing a third monomer component containing methyl methacrylate as a main component to form an outermost layer on the second layer. However, it is unavoidable that peculiar beautiful appearance and transparency that methacrylic resins possess are impaired by the incorporation, and improvement of the impact resistance is also insufficient. It is the actual circumstances that there has not been provided a resin composition, as demanded in the market, which exhibits a sufficient impact resistance with maintaining the properties of methacrylic resins without impairing the appearance and transparency and which has a good heat stability as required in molding.
It is an object of the present invention to improve the impact resistance of methacrylic resins without impairing the properties thereof such as appearance and transparency.
A further object of the present invention is to provide a methacrylic resin composition having excellent transparency, appearance and impact resistance as well as good weatherability, gloss and processability.